Liquid coating compositions, coated objects, and processes for making same



threading,

Patented Oct. 23, 1945 LIQUID COATING OBJECTS, AND SAME COMPOSITIONS,COATED PROCESSES FOR. MAKING Alger L. Ward, Drexel Hill, Pa., assignorto The United Gas Improvement Company, a corporation of Pennsylvania NoDrawing.

Application December 27, 1940,

\ Serial No. 371,988

Claims. (Cl. 117-132) This invention pertains generally to the coatingof surfaces and particularly to the coating of metals in sheet form.

The invention pertains more particularly to the coating of sheet metalwhich is to be fabricated into objects by stamping, bending, drawing,

turning, punching, and the like.

Machine operations, such as the foregoing, are particularly severe uponcoatings or films adhering to the sheet metal. and in many instances, itis extremely difllcult to obtain a formed object with a coating or filmsystem adequate for the environment to which the finished article is tobe subjected when in use. i

To illustrate, many types of films and particularly those made fromresinous materials, crack, check, striate, silk and/or peel whensubjected to the foregoing mechanical operations.

Because of the great economical advanta e f coating the sheet metalprior to the various forming operations, the importance of a film orfilm system which will withstand the various forming operations withoutinjury cannot be over-estimated.

Another quality of extreme importance, particularly in the case ofcertain uses to which the finished articles are to be put, is therelative insolubility and chemical inertness of the film or film system.

An Outstanding example of such ause is in the food packaging field. inwhich metal cans and metal foil wrappings are extensively used.

The term food is employed herein to mean that which is eaten or drunk orabsorbed for nourish ment or otherwise, and includes not only beveragessuch as beer, but also substances from which food is prepared, examplesof which are coffee beans, whether ground, or not, and tea leaves.

In the case of cans, for example, economical considerations make itextremely advantageous to apply the film or film system to the sheetmetal while in the fiat. The can parts are then out, shaped and joinedall in a manner well known in the art. Severe stresses are set up duringthe forming operations, particularly in the case of the die-drawing ofthe can ends. The can ends and portions of the can body are againsubjected to severe stresses during the can closing operation such as bythe seaming chuck, seaming rolls, and cooperating parts of the canclosing machine during the well known double-seaming can sealingoperation.

For instance, the die-drawing step produces in standing which, in turn,reacts chemically with with relativeLv sharp bends, but also aperipheral portion which is curled back upon itself.

A film or film system to be successful must withstand such and similarmetal working operations without peeling or rupturing or otherwisefailing in the slightest degree.

Metal caps are used in large quantity not only on glass bottles but alsoon certain types of metal containers, such as those for holdingbeverages.

In many cases, such caps are provided with threads for engagingcooperating threads upon the bottle or other container.

The operation for forming the threads in the metal caps is extremelysevere, since the metal is frequently stretched by as much as 100%during the forming operation. 1

In the food packaging field it is, of course, absolutely essential thatthe film or film system be not only completely insoluble and chemicallyinert, but also completely incapable of imparting taste or odor to thefood product.

In this connection, it is a well known factthat the ordinary tin liningis unsatisfactory in the case of certain foods of which grape juice,orange juice, and beer are outstanding examples.

Some foods develop hydrogen sulfide upon the tin lining to form tinsulfide. In case any of the iron is exposed, such as through cracks,black iron sulfide is formed.

Furthermore, in the food packaging field, the packaged foodstuff, aftersealing of the can, is in many cases, subjected to a sterilizationtreatment by the application of heat. Such treatment, by reason of theincreased temperatures involved, greatly accelerates any reactionscapable of taking place.

Numerous attempts have been made to find a lacquer which might beapplied over or substituted for the tin coating. Films made with pre-'viously known lacquers, as a rule,'however, have the can ends not onlyangles of very nearly 90 failed to have sufllcient adhesion and cohesionto resist forming operations, or they have failed to resist reactionwith foods, or they have failed in that they have imparted taste or odorto the foods.

This led to the adoption of a procedure whereby a coating compositionhaving good bonding properties was employed as a primer coat for a topcoat having proper food resisting and taste and odor characteristics, ofwhich the material known commercially as Vinylite is an outstandingexample. In turn, this presented the further problem not only of findingtwo such coating compositions which would bond properly with each other,but also of flnding'a primer coat which would not impart taste and odorto the food despite the top coat.

The product known commercially as Vinylite" though deficient as a primercoat is nevertheless, satisfactory as a top coat provided a proper bondthat will withstand not only the forming operations but also thesterilization treatment can be formed between it and the primer coat.

In this connection, many films and dual film systems develop acloudiness during the sterilization step, such cloudiness beinggenerally referred to as blushing. The resulting discoloration is veryundesirable from the standpoint of market appeal, since the averagehousewife looks with great disfavor upon any discoloration of the insidesurface of a can when removing food therefrom.

It follows that any film or 'film system to be suitable must not only becapable of resisting blushing, but must in itself have an acceptableappearance and preferably one suggesting utmost cleanliness.

Since films and film systems of the character under consideration arenecessarily extremely thin, the primer coat is preferably one capable ofdirect contact with the foodstufi' without chemical reaction and withoutimparting taste or odor thereto. Certain substances which mightotherwise be satisfactory as primer coats fail because they are capableof imparting taste and odor to foodstuffs through the top coat.

In addition to the foregoing, there are certain metals which areextremely difiicult to coat with ble and extensible and tenaciouslyadhering film upon drying with or without baking.

Methods for preparing the benzene-soluble catalytically polymerizedcyclopentadiene employed in my invention are described and claimed incopending application, Serial Number 194,523,

filed March 8, 1938, by Samuel G. Trepp, and copending applicationSerial Number 204,786, filed April 28, 1938, by Frank J. Soday.

The following are specific examples of the preparation of the desiredpolymer,

Example 1 was gradually added'from a mixing tank, maintained at atemperaturesufllciently low to prevent the volatilization of thecyclopentadiene. The mixture is preferably below room temperature whenit reaches the reaction kettle.

satisfactorily adhering films or film systems of any character. Examplesare zinc, zinc plate, magnesium and magnesium alloys, such as thematerial known commercially as Dow metal. In fact, practically allpreviously known resinous coating compositions fail to form asatisfactory bond with these materials.

In accordance with my invention, single film systems and multiple filmsystems having all of ing catalytically polymerized cyclopentadiene' andone or more additives comprising a substance ,or substances of awax-like nature with or without sulfur and/or a sulfur-containingsubstance. Drying of the applied film or films may be accom-- plishedwith or without the aid of heat.

Generally speaking, thecatalytically polymerized cyclopentadieneemployed in my liquid coating composition has the following properties.It is soluble in benzene, toluene, chloroform, carbon tetrachloride andhigh flash naphtha, and insoluble in alcohol, acetone, ether and water.For the purpose of convenience in the claims, these solubilitycharacteristics will be defined by the term benzene-soluble," though itis to be under stood that the actual presence of benzene in the liquidcoating composition or in the applied films is not implied. Preferably,my liquid coating composition, after admixture with a wax-like substancewith or without a sulfur-containing substance and/or sulfur (referred tohereinafter and in the claims for convenience and brevity as sulfurcontaining material) has other distinctive properties. Among'theseproperties is the ability to form a smooth, glassy, highly flexi- Therate of addition was so regulated that the contents of the reactionkettle were maintained at a temperature between 25-30 C. whilecirculating cooling brine through the jacket.

From 20 to 60 minutes were required for the addition of thecyclopentadiene-toluene mixture depending upon the efliciency of thecooling brine. When addition was complete, the brine flow was cut downso as to keep the temperature above 25 C. but below 50 C. and theproduct was agitated for an additional 1 hours.

5 pounds of water were now added to hydrolyze the catalyst so that thefluorine might later be removed as hydrogen fluoride by the lime. 4

After 30 minutes further agitation, '75 pounds a suction filter, and theproduct pumped through the filter. Any type of filter, such as a platefilter press, centrifuge, etc., might be employed,

The product was a 20% solution of the desired polymer.

In the above example, the particular temperatures chosen are more orless for expediency, but

it will be noted that at no time did the temperature exceed 100 C. oreven C.

vent local overheating.

Example 2 0.30 cubic centimeter of aluminum chloridediethyl ethercomplex is added to 60 grams of toluene with thorough agitation to forma suspension, emulsion or solution.

A mixture of 20 grams of ,cyclopentadienes and 20 grams of toluene isadded to the suspension during the course of 12 minutes,.the temperatureranging from 26-49 C. during the addition. The mixture is then agitatedfor an additional hour, after which 1 cubic centimeter of water isadded. This is followed by agitation for 15 minutes.

10 grams of quicklime (CaO) are now added to v Constant 'agitationandbrine cooling made it possibleto prethe reaction mixture followed byagitation for an additional hour.

grams of a suitable filter aid are then added, and the mixture filtered.

A filtered solution containing 16.4 grams of polycyclopentadiene is thusobtained.

Generally speaking, any other boron trifiuoride-organic solvent complexor aluminum chloride-organic solvent complex might be substituted in theabove examples.- Other methods for making benzene-soluble catalyticallypolymerized cyclopentadiene obviously may be employed.

The wax-like material, which is employed according to my invention, arehigh molecular weight compounds or mixtures thereof such as -may befound naturally in substances of animal Y and vegetable origin.Generally speaking, they include esters of higher acids and higheralcohols, although substances of mineral origin, for instance substancescomprising one or more higher parafiin hydrocarbons likewise areincluded in the scope of the term. Likewise, substances of syntheticorigin are included'as well as those naturally occurring.

As examples of wax-like materials may be mentioned the following:

Cetyl cerotate. (C1sI-Ia3.OOC.C2sH53); cetyl acetate, (C1sH33.00C.CH3);ethyl palmitate,

(CaH5.OOC.C15H31) (CH3.00C.C17H35) glyceryl stearate,(C3H5(C17H35COO)a); and spermaceti, a naturally occurring wax-likematerial comprising primarily cetyl palmitate.

Considering the wax-like fatty acid esters just named it may be saidthat especially effective additives comprise those in which the chainlength of the individual molecules varies broadly from about 18 to 57carbon atoms and particularly from about 18 to 43 carbon atoms. Theesters toward the upper end of the latter range are in general preferredprovided their solubility in the particular solvent containing thepolycyclopentadiene is not so low as to render their practicable useless desirable; Mixtures of such esters containing molecules of 28 to 36carbon atoms are especially satisfactory.

Excellent results are obtained when cetyl palmitate is used as theadditive, particularly when in the form of the crude material known asspermaceti such as found in the head of the sperm whale.

One or more wax-like materials may be added to the benzene-solublecatalytically polymerized cyclopentadiene.

The quantity of wax-like additive may preferably be from about 15 tobased upon the content of' polymer, although more or less may beemployed withsatisfactory results. Particularly desirable results areobtained when approximately 22% of wax-like additive is employed.

One or more sulfur containing substances are preferably employed asadditional additive although this material may be omitted if desired.

Any suitable quantity of sulfur containing ma terial, for example in theform of flowers of sulfur, may be employed of which from 1% to 15% andparticularly 10% based upon polymer con-.

tent is an example.

Usually, the addition of any sulfur-containing material is made prior tothe application of the liquid coating composition to the surface orobiii ject to be coated. For example, flowers of sulfur may be added tothe wax containing polycyclopentadiene prior to its application to thesurface to be coated.

However, any addition of sulfur-containing material may be made afterthe liquid coating composition has been applied to the object to becoated. This may be accomplished for example, by drying the coatedobject in an atmosphere comprising hydrogen sulfide and/or othersulfurcontaining material. In this case the sulfurcontaining material isabsorbed by the coating composition from the atmosphere.

Thus, the coated objects may be said to be coated with a dried film of aliquid coating composition comprising benzene-soluble catalyticallypolymerized cyclopentadiene in admixture with wax-like material with orwithout sulfur-containing material, and when 'sulfur containing materialis employed the coatings may be said to be dried in admixture withsulfur-containing material irrespective of whether the sulfur containingmaterial is first added or added by way of the drying atmosphere, orboth.

The completely dried films are generally insoluble, particularly in theordinary solvents.

I have found that by incorporating wax-like material with or withoutsulfur-containing material. with benzene-soluble catalyticallypolymerized cyclopentadiene, the properties of the dried resin films aredesirably modified, particularly with respect to their ability towithstand drastic metal-working operations such as the diedrawing stepsemployed to produce bottle caps or can ends from sheet metal.

It also appears that the addition of wax-like material with or withoutsulfur-containing material tends to reduce the rate of oxidation of thepolycyclopentadiene film which may be desirable in some instances. vThe'ratio of additive employed may be varied considerably, dependingupon factors such as the particular nature of the additive, the mannerof drying, etc. 7

For example, while I have employed wax-like materials as additives invarious concentrations from as low as 1% of the polycyclopentadienecontent to as high as 30% and higher with satisfactory results, I findthat a concentration of about from 15% to 25%, as for example 22% isparticularly satisfactory, especially when combined with sulfurcontaining material in concentrations of from about 1% to 15% andparticularly of about 10% of the polycyclopentadiene content. The,maximum quantity of either material that will ordinarily be used in anygiven case will, of course, depend somewhat 'upon the solubility of theparticular additive in the polymer solution, although it is conceivablethat some of the additive or additives may be present in finely divideddispersed form.

An example of the formation of a single film system'in accordance withmy invention is as follows:

Example 3 To a 20% solution of catalytically polymerized cyclopentadienein toluene is added 22% spermaceti, calculated on the polymer content ofthe solution. The resulting liquid coating composition is applied tosheet metal, such as tin plate, in such quantities that the final resinfilm whether applied in one coat, or several coats with or withoutintermediate drying such as by baking, will have a desired thickness,for example baked at a temperature rising from 86 ibility orextensibility.

the equivalent of about 2 milligrams per square inch of dry film.

The coated sheet is placed heated to a temperature of 250 F. for aperiod of about 8 minutes in order to insure satisfactory drying, thepolycyclopentadiene adding an oxygen from the atmosphere during thebaking. Alternatively, drying may take place at room temperature such asbetween 30 minutes and 6 hours.

Sheet metal thus coated is capable of withstanding drastic formingoperations such as encountered in the manufacture of cans or othercontainers, container caps and the like, without injury to the film.

Example 4 To a 20% solution of catalytically polymerized cyclopentadienein toluene is added 22% spermaceti, calculated on the polymer content ofthe solution. A tin platedsheet was coated with the resulting liquidcoating composition in sufllcient quantity to secure a desired finalcoating weight, for example, the equivalent of about 2 milligrams persquare inch after drying such asby baking.

The coated sheet was placed in an oven and F. (30 C.) to 266 F. (130 C.)over a period of 15 minutes while. maintaining a constant flow ofhydrogen sulfide through said oven and in con-' tact with said coatedsheet.

The metal sheet thus'coated is able to withstand drastic metal workingoperations, such as are employed in the manufacture of cans, caps,

and the like, without injuring the applied film.

Example 5 To a 24% solution of catalytically polymerized cyclopentadienein toluene is added 22% spermaceti, and sulfur, calculated on thepolymer content of the solution. The resulting liquidcoatin'gcomposition is applied to sheet metal, such as tin plate, insuch quantities that the final resin film whether applied in one coat,or several coats with. or without intermediate drying such as by bakingwill have a desired thickness, for example, the equivalent of about 2milligrams per square inch of dry film.

The coated sheet is placed in an oven and heated to a temperature of 250F. for a period of 8 minutes in order to insure satisfactory dryingduring which time the film takes up oxygen from the air Without loss ofadhesion, flex- Baking times may be, for example, between four minutesand thirty minutes. Theelevated temperatures employed favor the addingon of oxygen.

Sheet metal thus coated is ready for drastic forming operations, such asencountered in the manufacture of cans or other containers, bottle caps,screw caps, and the like. It will withstand extremely rough treatmentwithout cracking,

checking, striating, silking, peeling, loosening, or otherwise injuringthe coating.

When made into cans the coating is highly resistant to foods, imparts notaste or odor thereto, and is free from blushing during thesterilization treatment.

An example of the formation of a dual film system in accordance with myinvention is as follows:

Example 6 A tin plated sheet, or other metal sheet, is coated with asolution of polycyclopentadiene in in an oven and toluene, say of 20%polycyclopentadiene content, to which 22% spermaceti and 10% sulfurbased on polymer content have been added. The solution is applied insufilcient quantity to secure a desired final coating weight, say ofapproximately 1% milligrams per square inch after drying such as bybaking.

The coated sheet after suitable evaporation of solvent is placed in anoven and baked at a temperature of say 250 F. for a period of 5 to 10minutes, the polycyclopentadiene adding on oxygen from the atmosphereduring the baking.

Upon cooling, a solution of Vinylite is applied in sufficient quantitysuch that the dual film system will have a desired thickness afterdrying of the "Vinylite film such as with bakin say a thicknessequivalent to 4 to 6 milligrams per square inch of dry dual film.

The coated sheet is then re-baked in the same manner as with the primercoat.

Metalsheet thus coated with the dual film may be subjected to formingoperations such as those involved in the manufacture of caps, canelements and the like, without injury thereto.

It will be understood, of course, that broadly speaking, the top coat isnot limited to Vinylite, which is the co-polymer of vinyl acetate andvinyl chloride, but may be a polymer of any of the vinyl compounds usedas raw materials for the several vinyl resins; e. g., vinyl acetate,vinyl chloride or vinyl chloracetate. In fact, other types of resins maybe adapted for application as the top coat over my benzene-solublecatalytically polymerized cyclopentadiene containing additives asdescribed.

Vinyl resins suitable for use in'forming'the top coat of my inventionmay be formed from vinyl esters by known polymerization processes. Thepolymerization products of inorganic vinyl esters, such as vinylhalides, or those of organic vinyl esters, such as vinyl esters ofaliphatic acids, may be used.

I prefer to use vinyl resins resulting from the co-polymerization of'two or more vinyl esters. For example, vinyl resins having desirableproperties may be prepared by the co-polymerization of a vinyl halideand a vinylester of an aliphatic acid.

Products of the co-polymerization of vinyl chloride and vinyl acetate nproportions ranging from about 10% to 90% by weight of the chloride areparticularly desirable.

The commercial product sold under the trade name Vinylite falls in thelatter category.

The foregoing vinyl resins are substantially water-white and transparentand they are exceptionally resistant to acids, alkalies, and salts inthe presence of moisture and may be used to form flexible top coatswhich adhere exceptionally well to my primer coat, suchtop coat (like myprimer coat) being odorless and tasteless.

To a certain extent, the characteristics of the preferred vinyl resinsare retained when the vinyl resin is modified by the addition of asecond resin or gum, a cellulose ester, or a, high boiling solventhaving plasticizing 'or softening action on the resin. Due to thisproperty, the vinyl resins may be modified to meet specific requirementswithout materially altering the chemical properties of the resinsemployed as the top coat.

However, in the food packaging field, the commercial product sold underthe trade name Thisproduct is thought to result from thecopolymerization of about 85% of vinyl chloride with 15% vinyl acetate.

Since my films of polycyclopentadiene plus wax-like additive, with orwithout sulfur containing material, not only bond well to surfaces butalso are highly resistant to attack by foods, and do not impart taste orodor thereto, they may be used as top coats for primer coats of othermaterials, if desired. 7 It is, of course, understood that my liquidcoating composition may be used for both a' primer coat and a top coator in any other number of coats.

It will be understood that other sulfur-containing substances might beemployed as sulfur containing material instead of, or together with,those already described. Examples of these are hydrogen polysulfide,HZS: (believed to comprise a mixture of H232 and H283), andsulfur-containing rubber vulcanization agents or accelerators, such asthe product known commercially as Tuads (tetramethyl thiuram disulfide.

MeaN.CS.S.S.CS.N Mez) or butyl zimate (Bu2N.CS.S.Zn.S.CS.N Buz), eitherseparately or insuitable admixture with each other.

With respect to the temperature and time of, baking, I usually prefer torarely if ever exceed about 400 F. and at such temperatures a bakingtime not longer than about minutes to avoid any possible injury to thefilm. However, while my resin films may be safely subjected torelatively high temperatures for brief periods during baking, ingeneral, I find temperatures up to 350 F. with baking times up to 30minutes very satisfactory. With higher temperatures the baking time maybe correspondingly shortened to yield similarly satisfactory results.

I have found that a particularly satisfactory baking schedule isrepresented by a temperature of 250 F. for a period of 8 minutes.Another satisfactory baking schedule is represented by a procedurewherein the temperature during the bake is gradually raised from aboutroom temperature to the maximum desired temperature such as about 250 F.over a period such as from 15 to minutes. The advantage of a bakingschedule such as the latter is that the solvent is driven ofl? moregradually, thus minimizing or eliminating any tendency for the resinfilm to be ruptured by escaping solvent.

, While I refer to baking broadly and to heating in the presence of air"or an "oxygencontaining gas as a means of drying my coating or film, itis to be understood that the taking on of oxygen by the fihn need notnecessarily take place simultaneously with the heating or baking. On thecontrary, I may heat or bake the coatingor the coated object in anatmosphere substantially devoid of oxygen such as an atmosphere ofconcentrated HzS and/or in an inert atgmosphere as of nitrogen, carbondioxide, or the li e.

Additional drying or hardening of the film may result from the.absorption of oxygen after ex-' posure to the atmosphere.

,Thus the drying or hardening of a film of polycyclopentadienecontaining a wax-like material, with or without sulfur containingmaterial, may be secured (a) by baking or heating in anoxygen-containing and/or sulfur-containing atmosphere, or (b) baking inan atmosphere devoid of oxygen followed by exposure to anoxygen-containing atmosphere for a period of in an atmosphere devoid ofoxygen, followed by gpplication of a top coat, and then letting the ualfilm stand or season" in contact with an oxygen-containing atmospherebefore using the coated article for its intended purpose, (in thelast-named case, oxygen evidently penetrates or seeps through the topcoat to the primer coat), 01\ (d) applying and drying the primer coat inan atmosphere devoid of oxygen, coating with a top coat of another resinsuch as Vinylite," still in an atmosphere devoid of oxygen, .and heatingthe multiple-film system thus formed, still inan atmosphere devoid ofoxygen, or (c) any combination of any of the foregoing, or otherwise. Itwill be understood that an atmosphere devoid of oxygen may have presentsulfurcontaining material.

Since the resin coating resultin from (d) wherein the entire series ofoperations take place in an atmosphere devoid of oxygen is entirelysatisfactory for commercial use, it would appear that my modifiedpolycyclopentadiene films may be satisfactorily hardened either by heat,or by an oxygen-containing and/orsulfur containing environment or by anycombination thereof.

In fact, other drying or.hardening methods might be employed.

In coating sheet metal, for instance, excellent results may be obtainedby coating one side, baking that coating-and then coating the otherside, after which the sheet metal is again baked.

After drying or hardening my modified polycyclopentadiene films are,generally speaking, insoluble.

While the film thicknesses given are found to be extremely suitable forthe purpose, and particularly for metal container elements such as foodcontainers and caps, other film thicknesses may obviously be employedwithout. departing from the spirit of the invention.

While in the above specific examples toluene is used, it is to beunderstood that other suitable solvents may be employed of whichbenzene, xylene, ethyl benzene, naphtha, chloroform and carbontetrachloride are examples.

For the purposes of the claims the term "highly flexible and extensibleand tenaciously adhering film or its equivalent is intended to define afilm capable of withstanding the following test.

A tin panel of any convenient dimensions such as two by three inches iscoated on one surface with a solution of the given resin in toluene insuch quantities that the final film after baking will have a weight offrom 2 to 6 milligrams per square inch. The temperature of baking is,for convenience, 270 F. After baking for one hour and cooling, thecoated tin panel is bent backwardly on itself over a mandrel 1 inch indiameter through an angle of 180 with the coated surface outward. Theends of the panel are then bent back to their original position. Thefilm must withstand this manipulation without striation, loss ofadhesion, surface cracking or checking or apparent optical change.

While the foregoing particular description has,

film or film system is desired. The fabrication of toys from sheet metalfor instance, represents another important field of application for myinvention.

Thus, the resin film may be applied to metal I foil.

As an illustration, tin foil and aluminum foil, each of which is used topackage dairy products like butter and cheese, may be so coated. Ifdesired, these materials in molten form may be poured into molds'linedwith foil coated in accordance with my invention.

So too, lead foil, such as is used to package tea 1 leaves, maybe coatedin accordance with my in- M c e t l foil may be coated by any desiredprocedure. For example, the foil may be passed through a. solution ofthe coating material and the excess removed by means of doctor blades orrolls. Or a conventional roll type coating procedure may be employed andthe solvent removed and/or recovered in any suitable manner. Or'

the coating materialmay be poured or sprayed on the material to becoated and the excess removed by doctor blades or rolls, or simplyallowed to drain away.

If desired, metal foil may be strengthened by backing it with paper, orby laminating two or more foil layers. Forexample, a sheet of metal foilmay be coated on one side and the coated film system may be appliedduring or after any forming operations for converting the initialmaterial into the finished object. It is generally useful for coatingmetallic objects in general, whether fabricated from sheet metal or not,or whether pre-fabricated in whole or in part prior to application ofthe film or film system.

While it is preferred to employ cyclopentadiene as substantially thesole resin-forming hydrocarbon in initially preparing the catalyticallypolymerized polycyclopentadiene. which is then modified by additives inthe manner described, the presence or addition of relatively smallamounts of still other substances of a resinforming nature withconsequent modified results may be sometimes desirable, provided theoutstanding characteristics of the base material are not substantiallydestroyed. Though in man instances I prefer touse the homopolymer ofcyclopentadiene without other polymer, .the presence of a homo-polymerof methyl cyclopentadiene or a co-polymer of cyclopentadiene and methylcyclopentadiene, or both, in amounts up to of the order of from 10 to20% and possibly more, appears to have no deleterious effectparticularly for certain uses. This does not apply to resinous materialsin general and extreme care should be exercised in making any additions.

The presence of up to 20% or more of methyl cyclopentadiene in thestarting material from which the polycyclopentadiene resin is preparedappears to have no outstanding deleterious efrect, particularly forcertain uses, though I usually limit its presence or exclude italtogether. The absence of all other materials polymerizable under theconditions employed is preferred. In fact, for the preparation ofprotective films giving the best results from every'standpoint, it isfor the most part highly desirable that there be present in the startingmaterials no substantialquantities of any other materials (besides thecyclopentadiene and methyl cyclopentadiene) which will form a resinunder tion conditions prevailing.

My new liquid coating composition has other uses than that of forming aprotective surface. For example, it is an excellent adhesive or cementand serves admirably in this connection in various uses to whichmaterials of this type are put.

If desired, suitable coloring materials may be' added such as dyes,pigments, and lakes. The same applies with respect to the Vinylite"'topcoat. However, in the food packaging field, care should be exercisedwith respect to any such added substances so as not to'lower or. destroythe excellent qualities of the original material for this particularuse. 3

Since in the food packaging field the important consideration is thatthe resin in contact with the food be chemically inert, insoluble in thefoodstuil, incapable of imparting odor and taste thereto, and stronglyadherent to the enclosing wall, outside portions of the container orfoil may be left uncoated, or may be coated with other materials,particularly if suitable, or with m materials with or without modifyingagents besides those already mentioned, orotherwise.

In the specification and claims, the term sulfur-containing is intendedto embrace elemental sulfur as well as compounds containing one or moresulfur atoms in the molecule.

It is to be understood that the above specific examples are by way ofillustration. Therefore, changes, omissions, I additions, substitutions,and/or modifications may be made within the scope of the claims withoutdeparting from the spirit of the invention.

I claim:

1. A liquid coating composition comprising benzene-soluble catalyticallypolymerized cyclopentadiene resin, wax-like fatty acid ester, asulfurcontaining rubber vulcanizing agent, and a volatile solvent, saidresin being derived substantially entirely from said cyclopentadiene.

2. A liquid coating composition comprising benzene-soluble catalyticallypolymerized cyclopentadiene resin in admixture with spermaceti, saidresin being derived substantially entirely from said cyclopentadiene.

3. A composition of matter comprising a waxlike material, and abenzene-soluble resinous polymer of a material having as substantiallythe only resin forming content thereof one of a group consisting of (a)cyclo'pentadiene and (b) cyclopentadiene admixed with up to 20% methylcyclopentadiene. r

4. A composition of matter comprising a waxlike fatty acid ester havingbetween 18 and 57 carbon atoms, and a benzene-soluble resinous polymerof a material having as substantially the only resin-forming contentthereof one of a group consisting of (a) cyclopentadiene and (b)cyclopentadiene admixed with up to 20% methyl cyclopentadiene.

5. A composition of matter comprising spermaceti and a benzene-solubleres'nous polymer of a material having as substantially the onlyresinforming content thereof one of a group consistin the polymerizaof(a) cyclopentadiene and (b) cyclopentadiene admixed with up to 20%methyl cyclopentadiene.

6. A composition of matter comprising benzenesolube resinous polymer ofcyclopentadiene per se, and from 15% to 25% spermaceti based upon saidresinous polymer.

7. A composition of matter comprising a benzene-soluble resinous polymerof cyclopentadiene per se, from 1% to 30% spermaceti based on saidresinous polymer, and from 1% to 15% sulfurcontaining rubber vulcanizingagent based on said resinous polymer.

8. A formed film-coated article shaped by deformation of a metallic bodycoated with a dried film of a compOsition comprising a wax-like materialand a benzene-soluble resinous polymer of a material having assubstantially the only resinforming content thereof one of a groupconsisting of (a) cyclopentadiene and (b) cyclopentadiene admixed withup to 20% methyl cyclopentadiene, said formed film adhering tenaciouslyto the formed metal.

9. A formed film-coated article shaped by drawing a metallic sheetcoated with a dried film of a composition comprising a benzene-solubleresinous polymer of cyclopentadiene per se, from 1% to 30% spermacetibased on said resinous polymer, and from 1% to 15% sulfur-containingrubber vulcanizing agent based on said resinous polymer, said dried filmadhering tenaciously to the drawn metal.

10. A formed film-coated article shaped by drawing a metallic bodycoated with an oxidized resinous film, said formed film adheringtenaciously to the formed metal and being comprised preponderantly ofspermaceti, and a benzene-soiuble resinous polymer of a material havingas substantially the only resin-forming content thereof one of a groupconsisting of (a) cyclopentadiene and (b) cyclopentadiene admixed withup to 20% methyl cyclopentadiene.

11. A formed film-coated fOOd container shaped by deformation ofmetallic sheeting coated with a dried film of a composition comprisingspermaceti and a benzene-soluble resinous polymer of a material havingas substantially the only resinforming content thereof one of a groupconsist- 2 ing of (a) cyclopentadiene and (b) cyclopentadiene admixedwith up to 20% methyl cyclopentadiene.

12. A food package comprising a formed filmcoated metallic sheetingshaped by deformation of metallic sheeting coated with a dried film of acomposition comprising spermaceti, and a benzene-soluble resinouspolymer of a material having as substantially the only resin-formingcontent thereof one of a group consisting 01. (a) cyclopentadiene and(b) cyclopentadiene admixed with up to 20% methyl cyclopentadiene, saidfood package having at least the surface thereof which would otherwisecome in contact with the food to be packaged coated with the formedfilm, said formed film adhering strongly to the formed metal.

13. A process for producing a formed article coated with a formedprotective layer of synthetic resin which comprises coating metallicmaterial from which the article is to be formed with a compositioncomprising a wax-like material, and a benzene-soluble resinous polymerof a material having as substantially the only resin-forming contentthereof one of a group consisting of (a) cyclopentadiene and (b)cyclopentadiene admixed with up to 20% methyl cyclopentadiene, dryingsaid coating, and subjecting the coated article to shaping operations toproduce a formed article.

14. A process for producing a formed article coated with a formedprotective layer of synthetic resin which comprises coating metallicmaterial from which the article is to be formed with a compositioncomprising a benzene-soluble resinous polymer oi. cyclopentadiene perse, and from 1% to 30% spermaceti based on said resinous polymer, dryingsaid coating, and thereafter subjecting the coated article to shapingoperations to produce a formed article.

15. A process for producing a formed article coated with a formedprotective layer of synthetic resin which comprises coating metallicmaterial from which the article is to be formed with a compositioncomprising a benzene-soluble resinous polymer of cyclopentadiene per se,from 1% to 30% spermaceti based on said resinous polymer, and from 1% to15% sulfur-containing rubber vulcanizing agent based on said resinouspolymer, drying said coating, and subjecting the coated material toshaping operations to produce a formed article.

ALGER. L. WARD.

